Drainage control mechanism



Jan. 30, 1962 sHU TANG HAN ET AL 3,018,825

DRAINAGE CONTROL MECHANISM Filed July 24, 1958 United States Patent O 3,018,825 DRAINAGE CNTROL MECHANISM Shu Tang Han and Jerome P. Brezinski, Beloit, Wis., assignors to Beloit Iron Works, Beloit, Wis., a corporation of Wisconsin p Filed July 24, 1958,y Ser, No. 750,720 3 Claims. (Cl. 162-419) The invention relates to a paper forming machine, and more particularly, to improved drainage control at the forming section for a paper machine.

In one type of paper machine wherein the instant invention is particularly useful, the forming region of the machine comprises a looped forming wire with a rotatably mounted foraminous cylinder within the loop of the forming wire forelfective fibrous' web formation on the wire. A rotatably mounted foraminous forming cylinder may be used in the yabsence of a Wire, also. An inlet feeds stock onto the forami'nous cylinder along the region of the upper quadrant of the up-running side of the cylinder.- This arrangement is used in cylindertype paper machines wherein the forming wire is actually a Vpart of the cylinder or wherein a short looped forming wire is trained over the cylinder mold; and this yarrangement may also be used in a Fourdrinier type paper machine wherein the forming wire is trained around an open breast roll. In either arrangement the wire covers at least approximately the upper quadrant of the 11p-running or oncoming side of the rotating cylinder. Means are provided for applying suction or partial vacuum to the inner periphery of the cylinder, at least coextensive with the arc subtended by the inlet, and preferably over a larger arcuate area, so as to assist in drawing water through the foraminous cylinder surface (and the wire, if one is used). Various means may be used for creating a suction within the cylinder. For example, sealing means may be associated with the oncoming and off-running sides of the wire so as to enclose the entire cylinder in a housing and to permit the creation of a vacuum within the entire housing (between the sealing means). As another example, a large suction gland may be mounted within the interior of 'the cylinder with first sealing means near a radial plane through the bottom of the stock inlet and second sealing means near a radial plane through the top of the cylinder and suction may be created between such sealing means. Because of diiculties familiar to those skilled in the art, with sealing means frictionally engaging the interior surface of such cylinders, the term sealing means as used herein is intended to include means maintained sufficiently close to the inner periphery of the cylinder to constitute an effective seal without actual contact.

At high operating speeds, it becomes most important to control the flow of water through the foraminous cylinder surface. A substantial amount of water must pass through the foraminous cylinder surface in this upper quadrant at the up-running side thereof, but there is atendency for the water to pass through the foraminous surface rapidly at the point of initial impact by the stock and, by comparison, quite slowly farther up the quadrant. One application of the instant invention is a means of reducing variably the rate of Iinitial drainage of Water through the foraminous cylinder. The forces causing the drainage of water through the cylinder surfaces are substantially a combination of pressure in the slurry on the wire and vacuum in the region under the wire. As the wire and foraminous cylinder approach the forming zone the open parts of the foraminous cylinder structure from the top of the forming wire to the inside of the suction roll shell are substantially air filled and normally at atmospheric pressure. The application 3,018,325 Patented Jan. 30, 1962 ice of suction to the underside of the forming surface requires the evacuation of an appropriate quantity of air from the structure. Normally very short periods of time are required to obtain practically the full operating vacuum at the underside of the forming surface. The rate at which the vacuum will be developed at the underside of the forming surface is controlled in this invention by mounting a baffle in close running relation to the inner periphery of the foraminous cylinder so that air llow from the foraminous cylinder into the suction gland is retarded thereby retarding the rate of application of vacuum to the underside of the forming wire. In this way a substantial degree of control of the flow of water through the foraminous surface can be achieved. In this application the baffle is preferably mounted so that its closest proximity to the inner periphery of the foraminous shell is at or near a radial plane imagined as passing through the bottom edge of the stock inlet, whereat the greatest rush of water takes place with the initial impact ofthe stock against the foraminous cylinder.

The mechanism will operate in a similar manner if the open portions of the cylinder structure were lled with water prior to entering the drainage zone.

The baffle so used is preferably a rigid member having a generally cylinder surface mounted so that it can be rotated about a point at or near its closest proximity to the inner periphery of the cylinder. Such mounting furnishes a means of varying the control desired.

It is, therefore, an important object of the instant invention to provide an improved drainage control within a rotatable foraminous cylinder in a paper machine.

It is an additional object of the instant invention to provide for control of the abrupt change in static pressure which occurs in the stock stream as it moves from the enclosed channel of the inlet into the channel bounded in part by the foraminous surface.

It is another object of the instant invention to provide a paper machine comprising a rotatably mounted foraminous cylinder, an inlet feeding stock onto the up-running side of the cylinder for depositing a brous web thereon, means creating suction within the cylinder opposite said inlet, and baffle means opposite said inlet controlling the dow of water from the stock through said foraminous cylinder. The word opposite as used herein means substantially co-radial or subtending the similarly oriented arc.

Other and further objects, features and advantages of the present invention will become apparent to those skilled in the art from the following detailed disclosure thereof and the drawings attached hereto and made a part hereof.

The 4drawing shows a paper machine forming section in an essentially diagrammatic elevational view with parts broken away and parts shown in section. The forming section of the drawing, designated generally by the reference numeral 10, is a forming section for a cylinder-type paper machine which comprises a looped forming wire 11, a rotatably mounted foraminous cylinder or open faced roll 12 for effecting fibrous web formation on the wire 11 in the region 12a of approximately the upper quadrant of the up-running side of the cylinder 12, and guide rolls 13 mounting the wire. An inlet 15 feeds stock onto the oncoming side of the wire 11 on the cylinder 12. The wire travels in the directlon indicated by the arrow heads.

It will be noted that the bottom of the inlet 15a is opposite approximately the middle of the up-running side of the cylinder 12, whereas the top of the inlet 15b is considerably higher being, in fact, near the top of the roll 12. Sealing means 16a (in the form of a sealing strip mounted in a gland) are positioned approximately adjacent the bottom 15a of the inlet 15 and second sealing means 16b are mounted opposite approximately the top of the cylinder 12. As indicated generally, the sealing means 16a and 16b form a part of a suction gland indicated generally by the reference numeral 16 which is held against rotation within the cylinder 12 and it defines a suction area covering approximately the iirst quadrant 12a. Means for creating a suction in the suction area are indicated generally by a pump P connected to the suction area through an axially aligned conduit 16C. The roll 12 is rotatably mounted on bearings 12b (indicated diagrammatically).

A source of possible diillculty in the operation of a device of the type just described is that the initial impact of stock at approximately the bottom 15a of the inlet 15 tends to create an excessive dewatering at this region. In general it is desirable to have the rate of dewatering more uniform throughout the mouth of the inlet 15, so that initial very rapid dewatering is not desirable in the formation of certain types of paper. The instant invention provides a baille 17 opposite the inlet 15 for controlling the ilow of air and, in turn, the pressure diilerence affecting the ilow of water from the stock through the foraminous surface of the cylinder 12. 'Ihe baille 17 extends upwardly in close running relation to the inner periphery of the cylinder 12. As here shown, the baille extends from opposite the bottom 15a of the inlet 15 to about the middle 15e` of the inlet 15. The baille 17 is mounted on the iirst sealing means 16a here and is preferably a rigid member formed with a generally cylindrical surface of the same or less radii so that the top of the baille 17a can be adjustably positioned toward and away from the inner periphery of the cylinder 12 by means of a mounting rod 17b of adjustable length. It will be noted that the baille 17 is preferably mounted very close to the inner periphery near its bottom 17c, but tapering or slanting away from the inner periphery of the cylinder 12 as it extends upwardly toward its top 17a, This has the eilect of gradually reducing its interference with flow of air through the foraminous cylinder.

It will be understood that modiilcations and variations may be effected without departing from the spirit and scope of the novel concepts of the present invention.

We claim as our invention:

1. In a paper machine, in combination, a rotatably mounted foraminous cylinder, an inlet feeding stock onto the up-running side of the cylinder for depositing a fibrous web thereon, iirst sealing means within the cylinder opposite the bottom of the inlet, second sealing means within the cylinder opposite the top of the cylinder, means creating suction within the cylinder opposite said inlet between said sealing means, and baille means mounted on said rst sealing means and extending upwardly therefrom in close running relation to the inner periphery of said cylinder.

2. In a paper machine, in combination, a looped forming wire, a rotatably mounted foraminous cylinder within the loop of the wire, an inlet feeding stock onto the Wire on the up-running side of the cylinder for depositing a iibrous web thereon, means creating suction within the cylinder opposite said inlet, baille means opposite said inlet controlling the ilow of water from the stock through said foraminous cylinder, and adjustable means mounting said baille means, said baille means dening a tapered gap with the inner periphery of said cylinders.

3. In a paper machine, in combination, a looped forming wire, a rotatably mounted foraminous cylinder within the loop of the wire, an inlet feeding stock onto the wire on the uprunning side of the cylinder for depositing a ilbrous web thereon, means creating a suction within the cylinder opposite said inlet, a baille mounted opposite said inlet and having a generally cylindrical surface and positioned at an angle so as to form a tapered gap with the inner periphery of the cylinder, and a mounting means adjustably connected to the baille to adjustably move the baille toward or away from the inner periphery of the cylinder.

References Cited in the ille of this patent UNITED STATES PATENTS 480,770 Johnson Aug. 16, 1892 747,632 Parker Dec. 22, 1903 770,307 Parker Sept. 20, 1904 811,660 Parker Feb. 6, 1906 1,551,405 Kilberry Aug. 25, 1925 1,864,580 Brawn June 28, 1932 2,154,719 Berry Apr. 18, 1939 2,348,340 Goodwillie et al. May 9, 1944 2,717,539 Metcalf Sept. 13, 1955 FOREIGN PATENTS 244,249 Germany Mar. 5, 1912 450,639 Canada Aug. 24, 1948 736,149 Great Britain Sept. 7, 1955 

